The Rotating Algae Biofilm Reactor (RABR) designed and built by WesTech
The Utah Science Technology and Research (USTAR) initiative, a technology-based economic development programme funded by the state of Utah, has awarded a US$175,320 grant for development of a commercial algal application in the removal of nitrogen and phosphorus from municipal wastewater.
The grant, awarded by USTAR’s Industry Partnership Programme (IPP) to Professor Ronald Sims, PhD of Utah State University (USU), supports a unique collaboration with USU, WesTech Engineering and the Utah Central Valley Water Reclamation Facility (CVWRF). The IPP promotes the development, acceleration and commercialisation of innovative technologies by teaming industry and university research expertise to address specific technology challenges.
In addition to the utilisation of algae for the removal of nitrogen and phosphorus from wastewater streams, the grant will address subsequent biomethane production and the conversion of waste products into high-value soil amendment through anaerobic digestion. USTAR funds have been matched by WesTech and CVWRF for a total project size of US$350,000.
CVWRF currently uses activated sludge and trickling filter treatment of wastewater, followed by anaerobic digestion of the biosolids generated in the treatment processes. The biosolids are dewatered using a belt filter press. The liquid portion, referred to as pressate, is high in ammonia and phosphorus, and is warm. This liquid will be used as the food source to cultivate microalgae that naturally grow by up-taking the growth nutrients, phosphorus and nitrogen, from the wastewater. The algae can then be harvested to obtain biomass, which will be sent to the anaerobic digestion phase where biomethane is produced and captured and a stream of high-value compost fertiliser can be produced. This delivers a double-sided benefit, because in the process, the wastewater quality is improved by reducing the levels of phosphorus and nitrogen being recirculated back into the main flow stream of the treatment plant. This also reduces the need for costly chemical agents and additional unit processes, which are otherwise required to bring nitrogen and phosphorus levels into compliance.
Central to the project is the Rotating Algae Biofilm Reactor (RABR), an attached growth algae reactor designed and built by WesTech and based on a concept of algae biofilm developed by the Waste to Bioproducts Engineering Center (SWBEC) that is a part of the Utah State Biological Engineering Department. The biofilm reactor was designed for cultivating and harvesting large amounts of algae, with applications to large-scale municipal wastewater treatment plants. The RABR combines both algae cultivation and harvesting into one process, improving efficiency and reducing costs.
“Algal biofilm systems in wastewater treatment have emerged as an alternative to suspended algal growth systems, because of the ease of biomass harvesting and reduced costs in downstream processing,” Sims said. “Research studies at Utah State demonstrate that algal biofilms grown using the RABR are very effective in removing nitrogen and phosphorus nutrients from both municipal and industrial wastewaters.”
“We want to contribute our process and equipment expertise and become a significant contributor to the field of algae use for nutrient removal,” Rex Plaizier, CEO of WesTech, added. “We are committed to making the wastewater community economically self-sustaining on a long-term basis. That is what is appealing to us about this project, along with the chance to work with our neighbours in Salt Lake City to make a positive impact in advancing this technology.”
The CVWRF is designed to treat 75 million gallons (283 million litres) of wastewater each day and is one of the largest municipal wastewater treatment plants in the state of Utah. The CVRF is a model for meeting future state and national treatment requirements and for developing waste-to-value opportunities. Nutrients removed from the wastewater are used to enhance the production of biomethane that is already being generated on-site to offset 70 per cent of the facility’s energy needs. In addition, the algae can be mixed in with the facility’s compost to create a higher-value product fertiliser.
“This project, if successful, has the potential to reduce the large capital and operating expenses for our facility,” Dr Philip Heck, PhD, Assistant General Manager with CVWRF, said. “It could create valuable resource streams, and help bring commercial application for algae removal to market.”
“That three separate entities could come together to address a major industrial and environmental issue is a testament to the spirit of cooperation that makes Utah such a great place to develop technologies,” Dr Ivy Estabrooke, PhD, executive director of USTAR executive director, concluded. “We are excited to see IPP really gain steam as a vehicle for industry/university collaboration in the state.”